/*
 * Copyright (c) 2011-2012 Alexander Dubu
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * o  Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * o  Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * o  Neither the name Axil nor the names of its contributors may be used to
 *    endorse or promote products derived from this software without specific
 *    prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

package axil.definition;

import axil.framework.validation.Validated;
import axil.framework.validation.ValidationContext;
import axil.framework.xml.InputXML;

import static axil.framework.Functions.*;


/**
 * The XML-based definition of a parameter to a function.
 */
public class Parameter implements Validated {
	private static final int undefined = -1;

	public enum Kind {
		required,
		optional,
		repeating
	}

	private String name;
	private String type;
	private Kind kind;
	private String description;
	private int id;


	public Parameter(InputXML xml) {
		name = xml.text("name");
		type = xml.text("type");
		kind = xml.ordinal("kind", Kind.values(), Kind.required);
		description = xml.content("description");
		id = nextID();
	}


	/**
	 * Return a string by which this object's value can be identified. The
	 * string returned cannot be null, but may be empty.
	 */
	public String identity() {
		return require(name);
	}


	public Kind kind() 				{
		return kind;
	}
	public String type() 			{
		return type;
	}
	public String description() 	{
		return description;
	}


	public int id() {
		if (id == undefined) {
			throw abort("Reference to parameter ID, but not yet assigned.",
			            nv("parameter", name));
		}
		return id;
	}


	public void id(int id) {
		if (id != undefined) {
			throw abort("Attempt to redefine parameter ID.",
			            nv("parameter", name), nv("is", this.id), nv("attempted", id));
		}
		this.id = id;
	}


	/**
	 * Validate this object in the given context. Any problems detected with the
	 * correctness or completeness of this object are placed into the context.
	 * This method descends into its owned members, validating them as well.
	 */
	public void validate(ValidationContext context) {
		context.check("name", identifier(name),
		              msg(Definition.ns, "invalid-identifier"));
		context.required("type", type);
		context.required("description", description);
	}


	/**
	 * Compress this object, reducing its memory footprint as much as possible.
	 * A compressed object is still fully functional for script evaluation but
	 * may no longer possess complete metadata.
	 */
	void compress() {
		this.description = null;
	}


	String synopsis() {
		switch(kind) {
		case optional:
			return '[' + identity() + ']';

		case repeating:
			return identity() + "...";

		case required:
			return identity();

		default:
			throw unreachable();
		}
	}


	/**
	 * Return a string representation of this object. The string returned is
	 * never null.
	 */
	public String toString() {
		return this.identity();
	}
}
